diff -rup asterisk-1.6.1.0-orig/channels/chan_sip.c asterisk-1.6.1.0/channels/chan_sip.c
--- asterisk-1.6.1.0-orig/channels/chan_sip.c	2009-04-20 19:08:26.000000000 +0200
+++ asterisk-1.6.1.0/channels/chan_sip.c	2009-06-15 07:31:06.000000000 +0200
@@ -1022,23 +1022,24 @@ struct sip_auth {
 #define SIP_NAT_ALWAYS		(3 << 18)	/*!< DP: NAT Both ROUTE and RFC3581 */
 
 /* re-INVITE related settings */
-#define SIP_REINVITE		(7 << 20)	/*!< DP: four settings, uses three bits */
+#define SIP_REINVITE		(15 << 20)	/*!< DP: five settings, uses four bits */
 #define SIP_REINVITE_NONE	(0 << 20)	/*!< DP: no reinvite allowed */
 #define SIP_CAN_REINVITE	(1 << 20)	/*!< DP: allow peers to be reinvited to send media directly p2p */
 #define SIP_CAN_REINVITE_NAT	(2 << 20)	/*!< DP: allow media reinvite when new peer is behind NAT */
 #define SIP_REINVITE_UPDATE	(4 << 20)	/*!< DP: use UPDATE (RFC3311) when reinviting this peer */
+#define SIP_REINVITE_NEWBRANCH	(8 << 20)	/*!< DP: Genereate new branch parameter in via header */
 
 /* "insecure" settings - see insecure2str() */
-#define SIP_INSECURE		(3 << 23)	/*!< DP: three settings, uses two bits */
-#define SIP_INSECURE_NONE	(0 << 23)	/*!< DP: secure mode */
-#define SIP_INSECURE_PORT	(1 << 23)	/*!< DP: don't require matching port for incoming requests */
-#define SIP_INSECURE_INVITE	(1 << 24)	/*!< DP: don't require authentication for incoming INVITEs */
+#define SIP_INSECURE		(3 << 24)	/*!< DP: three settings, uses two bits */
+#define SIP_INSECURE_NONE	(0 << 24)	/*!< DP: secure mode */
+#define SIP_INSECURE_PORT	(1 << 24)	/*!< DP: don't require matching port for incoming requests */
+#define SIP_INSECURE_INVITE	(1 << 25)	/*!< DP: don't require authentication for incoming INVITEs */
 
 /* Sending PROGRESS in-band settings */
-#define SIP_PROG_INBAND		(3 << 25)	/*!< DP: three settings, uses two bits */
-#define SIP_PROG_INBAND_NEVER	(0 << 25)
-#define SIP_PROG_INBAND_NO	(1 << 25)
-#define SIP_PROG_INBAND_YES	(2 << 25)
+#define SIP_PROG_INBAND		(3 << 26)	/*!< DP: three settings, uses two bits */
+#define SIP_PROG_INBAND_NEVER	(0 << 26)
+#define SIP_PROG_INBAND_NO	(1 << 26)
+#define SIP_PROG_INBAND_YES	(2 << 26)
 
 #define SIP_SENDRPID		(1 << 29)	/*!< DP: Remote Party-ID Support */
 #define SIP_G726_NONSTANDARD	(1 << 31)	/*!< DP: Use non-standard packing for G726-32 data */
@@ -8046,7 +8047,7 @@ static int reqprep(struct sip_request *r
 		seqno = p->ocseq;
 	}
 	
-	if (sipmethod == SIP_CANCEL || sipmethod == SIP_INVITE) {
+	if (sipmethod == SIP_CANCEL || (sipmethod == SIP_INVITE && !ast_test_flag(&p->flags[0], SIP_REINVITE_NEWBRANCH))) {
 		p->branch = p->invite_branch;
 		build_via(p);
 	} else if (newbranch) {
@@ -21238,6 +21239,8 @@ static int handle_common_options(struct 
 				} else if (!strcasecmp(word, "nonat")) {
 					ast_set_flag(&flags[0], SIP_CAN_REINVITE);
 					ast_clear_flag(&flags[0], SIP_CAN_REINVITE_NAT);
+				} else if (!strcasecmp(word, "newbranch")) {
+					ast_set_flag(&flags[0], SIP_REINVITE_NEWBRANCH | SIP_CAN_REINVITE | SIP_CAN_REINVITE_NAT);
 				} else {
 					ast_log(LOG_WARNING, "Unknown canreinvite mode '%s' on line %d\n", v->value, v->lineno);
 				}
diff -rup asterisk-1.6.1.0-orig/configs/sip.conf.sample asterisk-1.6.1.0/configs/sip.conf.sample
--- asterisk-1.6.1.0-orig/configs/sip.conf.sample	2009-04-02 19:14:08.000000000 +0200
+++ asterisk-1.6.1.0/configs/sip.conf.sample	2009-06-15 08:06:45.000000000 +0200
@@ -615,6 +615,11 @@ srvlookup=yes                   ; Enable
                                 ; instead of INVITE. This can be combined with 'nonat', as
                                 ; 'canreinvite=update,nonat'. It implies 'yes'.
 
+canreinvite=newbranch		; Generate a new branch parameter in via header of reinvites.
+				; Can also combined with 'nat' and implies 'yes'.
+				; Reinvites will fail otherwise with Patton Media Gatways or
+				; SEN OpenStage Phones
+
 ;----------------------------------------- REALTIME SUPPORT ------------------------
 ; For additional information on ARA, the Asterisk Realtime Architecture,
 ; please read realtime.txt and extconfig.txt in the /doc directory of the